In 'Advanced > Debug Settings', set 'RenderDynamicLOD' and 'RenderUseFarClip' to 'FALSE', so that objects in the distance are rendered sharply.

In 'Edit > Preferences > Network', set 'Maximum Bandwidth' to the maximum.

Snapshots

In the Advanced menu, enable 'High-res Snapshot'. When you take a snapshot, switch 'Basic Shaders' back on in the Graphics Preferences, and enable 'Anisotropic Filtering' and 'Antialiasing' in 'Hardware Options'. Change the output format to PNG, set 'Size' to 'Custom' and set the width and height as high as they'll go. See Torley Linden's Guide to High-Quality Photography for more.

Purchasing

You can buy objects directly in Second Life, but it's easier through XstreetSL, which has descriptions and ratings. Whichever you choose, buying currency involves two steps: transferring US dollars into your account using PayPal, for example, then using that to buy Linden dollars on the currency exchange. Once you have L$, these can be used to purchase objects.

Once packaged objects are in your inventory, drag them onto a patch of land to rez them, right-click the rezzed object and choose 'Open', then choose 'Copy To Inventory'. Now you can make use of the objects.